The man, who has not been named for fear of affecting his career, and was off duty at the time, claimed the beings were inspecting a new crop circle in the middle of a field.

According to a video released about the sighting, the officer saw distant activity and got a strange feeling before stopping his car to investigate.

The video claims as he approached the three “men”, he could see they were all taller than six feet, with long blond hair, but then heard “the sound of static electricity” before the trio ran away ”faster than any man he had ever seen”.

The officer described the events which allegedly happened on July 6, 2009, as almost “unreal”.

He said he drove straight back to Marlborough in Wiltshire, and later contacted paranormal experts.

He enlisted the help of Andrew Russell, a crop circle investigator.

Mr Russell has described what the officer saw.

He said: “At first he thought they were forensic officers as they were dressed in white coveralls. He stopped his car and approached the field.

“The figures seemed to be inspecting the crop. When he got to the edge of the field he heard what he believed to be a sound not dissimilar to static electricity.

“This crackling noise seemed to be running through the field and the crop was moving gently, close to where the noise was.

”He shouted to the figures who, at first, ignored him, not glancing at him. When he tried to enter the field they looked up and began running.”

“He said the men ran faster than anyone he had ever seen.”

The officer said: “I’m no slouch but they were moving so fast. I looked away for a second and when I looked back they were gone.

”I then got scared. The noise was still around but I got an uneasy feeling and headed for the car. For the rest of the day I had a pounding headache I couldn’t shift.”

A promotional blurb for the video speculated: “They all appeared deeply interested and analysing the crop circle – was it them who made it, or possibly was it their fellow colleagues from a far!?

“The crop circle had been there in the field for a few days before this incident.”

Another crop circle expert, Colin Andrews, who investigated the incident alongside Mr Russell, said he is ”convinced” by the police officer’s story and does not see any reason at all why the Officer would of made this story up.

He said: ”I am quite convinced the officer had an experience that day and one that we have not fully explored.

“I think with the unusual movement of the being and the poltergeist experiences there is too much additional information to say that is something in nothing.”

The experts suggest the three were part of an alleged alien race known as Tall Whites, which have been the subject of numerous sightings over the years.,

A Wiltshire Police spokesman said: ”The police officer was apparently off duty when this happened so we have no comment to make because it is a personal not a police matter.”